Square waves are a cool signal. They contain lots of frequency response info, but, unlike the frequency response plot, also contain some visible information on the phase and time response of the headphones. I highly recommend them...

Editors Note - I had a good laugh reading well known headphone enthusiast ClieOS' (Tai Ming Sow) article as some of his recommendations are very familiar to me and have already been reviewed favorably at InnerFidelity, and some I had never even heard of the company before. The number and variety of IEMs Tai has heard is spectacular.

I should mention Tai lives in Malaysia, and a couple of the headphones he recommends are not available in the U.S. Thanks for the recommendations Tai.

Editor's Note: This article was nearly complete when I read of Steve Jobs's death last night. I think the conclusions herein are telling of his passion for making "insanely great" products ... right down to the last detail.

A couple of weeks ago, Steve Guttenberg wrote an article on his Audiophiliac blog entitled, "The Worst-Sounding Audio Product." In it he "aimed [his] sights on the worst sounding product regularly used by millions of people:" the stock Apple iPod ear-bud headphones. There may be some truth in that, but he also said, "Apple is an amazingly innovative company, but it's incapable of selling a decent set of headphones under its own name."